Efficient pulse sequence for multisection dual-repetition time MR image acquisition

A magnetic resonance imaging pulse sequence was developed in which multisection spin-echo image data are simultaneously acquired for two repetition time (TR) intervals (TR1 and TR2) in one imaging sequence. In a conventional multisection image at a single TR, the number of sections is limited to TR/TS, where TS is the readout time. With this new sequence, the number of sections that can be imaged at both TRs in one acquisition is equal to (TR1 + TR2)/(TS1 + TS2), where TS1 and TS2 may be different for the two TRs. Imaging time is equal to that for a single image at a TR of TR1 + TR2. Clinical images were obtained with the new sequence from 15 patients and compared with images acquired at the same TR/TE by means of standard multisection single-TR methods. Relative image quality was assessed by three radiologists in 37 comparisons. In general, the dual-TR results at the long TR were judged equivalent to those from a single-TR image. Dual-TR results at the short TR had a modest reduction in contrast, but in none of 15 cases were any pathologic features missed.